Various amusing computer game software have been developed for home video game machines with which various games can be played by changing CD-ROMs. Such video games are very popular for amusement. Sometimes, the supply of popular game software does not catch up with the demand, and CD-ROMs carrying game software are traded at high prices. Counterfeits of such CD-ROMs are continually being discovered.
Producers of game software have made various security systems to prohibit counterfeiting of game software which is the fruit of development by producers with considerable amounts of investment of money, time and effort.
In one such security system, the agreement of data, such as a special code incorporated into program information read from a CD-ROM with data stored in advance in a main body of a game machine is judged to allow access to the CD-ROM.
However, in such conventional security systems, where security depends on the agreement between program information stored in a storage medium and data stored in a main body of a game machine, security would be unavoidably released when security data are decoded. If once the security is released, means for expelling counterfeits are limited, which makes it difficult to effectively expel counterfeits from the market.
Known security systems for improving such disadvantages are described in Japanese Patent Laid-Open Publication No. 101349/1983, U.S. Pat. No. 4,454,594, U.S. Pat. No. 4,442,486, U.S. Pat. No. 4,462,076, etc.
In the security system disclosed by the known art, a coded identifier indicative of a trademark, copyright or the like, is stored in a program memory in a video game cartridge, and a reference identifier is stored in a computer system in a video game machine. When the cartridge is loaded into the video game machine, the reference identifier in the video game machine is compared with the identifier read from the program memory.
When the comparison finds agreement between the reference identifier in the video game machine and the identifier in the program memory, the identifier, i.e., a trademark, copyright or the like, is displayed on a monitor display. When they do not agree with each other, the operation of the video game machine is stopped, prohibiting the execution of the program.
For a counterfeiter to supply a program operative on video game machines, it is necessary to incorporate a coded identifier corresponding to a trademark, copyright or the like which agrees with a reference identifier stored in advance in authentic game machines. This is an infringement, in principle, of proprietary rights, such as the trademarks, copyrights or the like.
In a conventional security system, unless a counterfeiter displays a trademark, copyright or the like corresponding to a reference identifier visibly on the exterior surface of, e.g., a cartridge, legal accusation is difficult, as property right infringement is based only on visually observed trademarks, copy right or the like. Hence, conventional security systems are at a disadvantage and make it difficult to seek protection under trademark acts, intellectual property laws, etc.
A first object of the present invention is to provide an information storage medium incorporating a novel security system which can effectively expel counterfeits or unauthorized copies and an electronic device using the same.
A second object of the present invention is to provide an information storage medium which can effectively expel counterfeits even when its security system is deciphered, and an electronic device using the same.
A third object of the present invention is to provide an information storage medium which can effectively expel counterfeits, and an electronic device using the same.
A fourth object of the present invention is to provide an information storage medium which can easily detect a specific indication in a security system, and an electronic device using the same.